ORIGINAL: 2slow2matter
On range, you're assuming that the TX is at the same elevation as the RX, which it will not be. The average beginner will fly at 300 feet plus high, so you need to add that into your figures as well....
I made no assumptions of any kind and the difference is tiny.
At 1500 feet out and 300 feet up, you are 1530 feet away. 30 foot difference or about 2%. And radio range is actually better higher up, so it is a wash.